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More Moon and Jupiter

February 7, 2011

The crescent Moon and the planet Jupiter stage a nice encounter in the western sky this evening. Jupiter is below the Moon, and looks like a brilliant star.

If you look carefully, you might notice a little color in Jupiter -- a hint of cream or ivory.

The color comes from globe-encircling bands of clouds atop the giant planet's atmosphere. The clouds are colored shades of white, tan, brown, and even orange by ammonia, sulfur, and other chemical compounds.

Each band is stretched all the way around Jupiter by the planet's high-speed rotation. Jupiter is far larger than Earth, yet it rotates on its axis in just 10 hours. That means a spot at Jupiter's equator whirls along at about 28,000 miles an hour. At that speed, you could go all the way around Earth in less than an hour.

But the rotation speed slows dramatically as you move away from the equator. That difference in speed stretches the clouds into bands that go all the way around the planet. The bands alternative between light and dark colors.

Jupiter's rotation also creates jet streams that blow along the boundaries between bands. These winds can reach speeds of hundreds of miles an hour.

If you look at each band up close, though, you see that they contain ripples and swirls that look like abstract paintings. But they're all painted in the same general palette -- colors that meld together to make Jupiter look like a shining ivory beacon in the night sky.


Script by Damond Benningfield, Copyright 2010


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